This invention relates to the manufacture of filtration bags for filtering liquids, such as water. Bags of this type are used in various industries and are made by seaming together two flexible sheets of a material suitable for filtering purposes.
In the past, seaming has been accomplished by stitching or sewing the sheets together. Sewing uses consumables, i.e. thread, and leaves pin holes in the material through which unfiltered liquid can escape. The use of adhesives is slow, is expensive, and produces inconsistent results.
Therefore, there has been the need to manufacture filtration bags in a more reliable and inexpensive manner, minimizing labor costs, yet providing highly consistent and reliable results. Of particular importance are leak-proof joints, uniform and repeatable results, elimination of consumables and retention of pliability of the manufactured bag.
These and other objects have been achieved by the present invention using a welding process in which sheets of thermoplastic material are vibration welded together along a desired seam line for forming a bag.